A pre-connection method for building substrate interfaces

Abstract

The present application relates to a kind of pre-connection methods of construction substrate interface, sequentially include the following steps: 1) the surface of two construction samples is processed flat;2) two construction samples are docked and stacked into the sample table in the furnace cavity;3) by pressure system, two construction samples are applied from top to bottom stress P1;4) the furnace cavity is vacuumized, and temperature field is applied to construction sample, temperature field setting process: first with heating rate V1 construction sample is rapidly heated to T1, with heating rate V2 construction sample is slowly heated to T2, keep warm for a period of time, V1> V2, T1< T2;5) when temperature reaches T2, by pressure system, two construction samples are continued to be applied from top to bottom stress P3, P3> P1, keep pressure time t2 after or make construction sample with strain rate (10 ‑5 ~10 ‑1 )s ‑1 Plastic deformation occurs, and after strain reaches (5%~60%), stress is reduced to P2 and kept pressure, P3> P2> P1.Effective connection of connection is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of realizing the connection of construction substrates, and particularly relates to a pre-connection method of a construction substrate interface. BACKGROUND

[0002] Metal materials are usually difficult to be processed in one step due to shape, specification, property and other reasons, and need to be completed by material connection technology. Material connection methods mainly include welding, bonding, riveting and the like. Among them, welding is the most commonly used way to realize the connection of metal materials. Solid-state connection technologies such as friction welding, diffusion welding and explosion welding have been widely used in the fields of aerospace, nuclear power, electronics and power, automobile manufacturing and the like due to the advantages of non-melting of base material, small heat-affected zone and large welding strength.

[0003] At present, the substrate construction connection method used in metal construction forming technology can realize the effective connection of part of materials. For example, Chinese Invention Patent "Homogeneous Metal Construction Forming Method", with the patent number ZL201511026272.X (authorized publication number CN105522349B) discloses a homogeneous metal construction forming method including preparing a plurality of base elements, the plurality of base elements being made of the same material; stacking the plurality of base elements into a predetermined shape; packaging the plurality of base elements stacked into the predetermined shape into a preform blank; welding the interfaces between the plurality of base elements by forging to make the preform blank into a blank; and forging the blank. The above patent realizes the homogeneous metal construction forming, but the substrate construction connection method used has complicated procedures and still has the following defects:

[0004] 1. The base elements after surface treatment need to be stacked in order and vacuum sealed and welded, the technical requirements in the welding process are high, the working environment is harsh, and a certain heat-affected zone will be left on the surface of the blank.

[0005] 2. The stacked blank after sealing and welding needs to be transported to a heat treatment equipment for pre-forging heat treatment, and after the pre-forging heat treatment is completed, the high-temperature hot metal block needs to be immediately transported to the forging press equipment for high-temperature forging and welding, and after the high-temperature forging and welding is completed, it needs to be immediately transported to the heat treatment equipment for long-time heat preservation. These series of operation processes belong to high-temperature operation, which is difficult to work and the heat dissipation is serious.

[0006] 3. The high-temperature transportation and forging and welding process is completed in a non-vacuum environment, and a thick oxide skin will be formed on the surface of the stacked blank, and if the oxide skin is not treated well, it will be pressed into the blank during deformation to form surface defects such as folding, cracking and pits.

[0007] 4. Although the interface of the stacked blank is vacuum sealed and welded, the thickness of the interface oxide layer is still large and the oxide layer is very difficult to break down; under the action of no external field, the insoluble oxide forces the overall construction temperature to be high, which is easy to cause the blank to be overburned and scrapped;

[0008] 5. Existing substrate construction and bonding methods require too long a heat preservation time for the free diffusion of elements and long-range migration of interfaces; for non-ferrous metals, which are more prone to forming interface oxides, an effective method has not yet been identified.

[0009] Therefore, there is an urgent need to further improve the interface connection method for stacked blanks in metal construction technology. Summary of the Invention

[0010] The first technical problem to be solved by the present invention is to provide a pre-connection method for building substrate interfaces that reduces the thickness of the oxide layer at the interface and promotes the decomposition and diffusion of oxides at the interface, in light of the current state of the prior art.

[0011] The second technical problem to be solved by the present invention is to provide a pre-connection method for constructing a substrate interface by using external field assistance to achieve rapid or seamless connection of metal billets.

[0012] The third technical problem to be solved by the present invention is to provide a method for pre-connecting the interface of a building substrate with high strength and good quality at the joint interface.

[0013] The technical solution adopted by the present invention to solve the first technical problem mentioned above is: a pre-connection method for constructing a substrate interface, characterized by comprising the following steps in sequence:

[0014] 1) After smoothing the surfaces of the two constructed samples, grind and clean them;

[0015] 2) Connect and stack the two constructed samples in the sample stage inside the furnace chamber;

[0016] 3) Apply a downward stress P1 to the two structural samples using a pressurization system to pre-fix them;

[0017] 4) Evacuate the furnace chamber and heat the constructed sample inside the chamber, i.e. apply a temperature field to the constructed sample. Temperature field setting process: first heat the constructed sample rapidly to T1 at a heating rate V1, then slowly heat the constructed sample to T2 at a heating rate V2 and hold it at that temperature for a period of time, where V1 > V2 and T1 < T2.

[0018] 5) When the temperature reaches T2, continue to apply a downward stress P3, where P3 > P1, to the two constructed samples using the pressurization system. After holding the pressure for t2, or until the constructed samples are subjected to a strain rate of (10... -5 ~10 -1 )s -1 Plastic deformation occurs, and after the strain reaches (5% to 60%), the stress is reduced to P2 and held at pressure, P3 > P2 > P1, that is, a changing stress field is applied to the constructed sample.

[0019] Preferably, in step 4), the stress is always kept as P2 during the heating process; the temperature T2=(0.6-0.85)T m , T m is the melting point of the material. In the holding process, the provision of the pressure-keeping stress P2 can keep the two built-up samples in a closely bonded state, and the combined action of the stress field and the temperature field can provide the necessary conditions for the interface metallurgical bonding, thus helping to improve the connection quality of the built-up joint.

[0020] Preferably, in step 5), the stress P3=(1.2-1.5)σ 0.2 , P2=(0.5-0.8)σ 0.2 , σ 0.2 is the high-temperature yield strength of the material of the built-up sample. In the above deformation stress P3, the built-up sample is kept at a certain strain rate, and the deformation stress P2 can provide a larger stress field under the condition of no continuous deformation.

[0021] Preferably, in step 4), V1 is 10-15℃ / min, V2 is 1-5℃ / min, T1 is 400-1000℃, T2=450-1200℃, P1 is 5-10MPa, P2=10-15MPa, P3=30-50MPa.

[0022] The technical scheme adopted by the present application to solve the above-mentioned second technical problem is that: after step 5), an electric field is applied to the built-up sample from top to bottom, the rated power of the electric field transformer in the electric field system generating the electric field is 20KW, the maximum working voltage of the electric field is 10V, and the maximum working current is 2000A, the electric field with the current density I1 of the electric field electrode is applied to the built-up sample, the electric field is kept for t1 time, I1 is 0-400A / cm 2 , t1 is 0-60min.

[0023] The introduction of the above-mentioned electric field can generate local micro-area high temperature at the built-up interface, effectively decompose the interface oxide layer, and at the same time avoid the overburning of the master batch caused by the overall high temperature of the material. In addition, the electric field is introduced at the same time of applying the stress field to the built-up sample, and the electric field thermal effect and electric field force promote the decomposition and diffusion of the oxide at the built-up interface.

[0024] The technical scheme adopted by the present application to solve the above-mentioned second technical problem is that: after step 5), an ultrasonic field is applied to the built-up sample, an ultrasonic probe for ultrasonic treatment of the built-up sample is arranged below the sample table, and the height of the sample table is adjusted as needed, that is, the distance between the interface of the two built-up samples and the ultrasonic probe is adjusted to L, wherein L is an integer multiple of the wavelength of the ultrasonic wave, so that the interface is located at the superposition position of the ultrasonic wave peaks.

[0025] The introduction of the above ultrasonic field can make the micro-undulation at the built-up interface fully contact and grind, break the interface oxide, and reduce the residual stress at the built-up interface. In addition, the ultrasonic vibration is beneficial to breaking and decomposing the built-up interface oxide when the stress field is applied to the built-up sample and the ultrasonic field is introduced.

[0026] Preferably, the rated power of the ultrasonic generator electrically connected with the ultrasonic probe is 3KW, the rated frequency is 20KHz, the distance L between the built-up sample interface and the ultrasonic probe is 12cm, the maximum amplitude of the ultrasonic probe is 20μm, and the amplitude transmitted by the ultrasonic probe to the built-up sample interface is substantially 1μm. The micro-amplitude vibration will not cause macro-deformation or lateral dislocation of the built-up sample, and has a certain stimulating effect on improving the microstructure of the interface.

[0027] The technical scheme adopted by the present application to solve the third technical problem is that: after step 5), an ultrasonic field and a top-down electric field are simultaneously applied to the built-up sample, the rated power of an electric field transformer in an electric field system for generating the electric field is 20KW, the maximum working voltage of the electric field is 10V, and the maximum working current is 2000A; an ultrasonic system generates an ultrasonic field, the rated power of an ultrasonic generator in the ultrasonic system is 3KW, the rated frequency is 20KHz, an ultrasonic probe for ultrasonic wave treatment of the built-up sample is arranged below the sample table, the distance L between the built-up sample interface and the ultrasonic probe is 12cm, the maximum amplitude of the ultrasonic probe is 20μm, and the amplitude transmitted by the ultrasonic probe to the built-up sample interface is substantially 1μm. In this way, under the auxiliary action of the external field (ultrasonic field and electric field), the strength and quality of the built-up joint interface are improved.

[0028] After the synergistic action of the multiple physical fields (temperature field, stress field, electric field and ultrasonic field), the refractory interface oxide has been broken and decomposed, and the interface partial region has been healed, that is, the built-up interface is rapidly healed. Since the ultrasonic field and the electric field are applied to the built-up sample during high-temperature deformation, the micro-undulation in the interface region fully contacts, the oxide layer is further broken and decomposed, the refractory oxide is accelerated to dissolve and atom diffusion and interface migration occur, and the built-up interface is effectively healed.

[0029] Further improve the strength of the interface connection, after the ultrasonic field and the electric field end, the temperature field and the stress field should continue to act for a period of time, the holding temperature is (0.6-0.85)T m , T m is the melting point of the material; the holding time is 0h-2h; the holding stress is (0.5-0.8)σ 0.2 , σ 0.2The pressure holding time is 0h-2h for building the high temperature yield strength of the material of the sample. Thus, after the electric field and the ultrasonic field are ended, the temperature field and the stress field continue to act for a period of time, which can make the decomposed interface oxide atoms diffuse into the two side matrixes in a long-range and uniform manner, and form a uniform connection joint.

[0030] Preferably, the building sample is one of magnesium alloy, aluminum alloy, ultra-fine grain nanometer carbon tube aluminum base composite material, 316H stainless steel and the same homogeneous metal.

[0031] Compared with the prior art, the pre-connection method for building the substrate interface has the advantages that: the building sample to be connected is simply cleaned, and the two building samples are butted and stacked, then the stress from top to bottom is applied to the two building samples, the building samples are heated, the stress P3 from top to bottom is further applied to the building samples, and the stress is reduced after pressure holding or after a certain strain amount is generated, the stress field is applied to the building samples to make them generate obvious plastic deformation, the building interface generates obvious plastic deformation under the action of the temperature field and the pressure field to effectively combine, even if no obvious plastic deformation is generated, the effective combination is realized in the process of isostatic pressure high temperature creep, the thickness of the oxide layer at the connection is small, and even the breaking and decomposition of the oxide layer are beneficial to the absence of the oxide layer, and the effective connection of the connection is realized. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The sectional view of the metal building device of Example 1;

[0033] Figure 2 The sectional view of the metal building device of Example 1 from another angle;

[0034] Figure 3 The metallographic diagram of the interface structure of the building sample of the ultra-fine grain aluminum base composite material in Example 1;

[0035] Figure 4 The scanning diagram of the interface structure of the building sample of the ultra-fine grain aluminum base composite material in Example 1;

[0036] Figure 5 In (a), the metallographic diagram of the interface structure of the building sample of the AZ31 magnesium alloy in Example 2, and in (b), the scanning diagram of the interface structure of the building sample of the AZ31 magnesium alloy in Example 2;

[0037] Figure 6 In (a), the metallographic diagram of the interface structure of the building sample of the AZ31 magnesium alloy in Example 3, and in (b), the scanning diagram of the interface structure of the building sample of the AZ31 magnesium alloy in Example 3;

[0038] Figure 7 The process curve of the temperature field selected in Example 4 (Case 1);

[0039] Figure 8 (a) is a metallographic image of the interface structure at the joint of the sample constructed in Example 4. Figure 8 (b) is a scanned image of the interface structure at the joint of the sample constructed in Example 4 of this embodiment;

[0040] Figure 9 (a) is a metallographic image of the interface structure at the joint of the sample constructed in Example 5 (Case 2). Figure 9 (b) is a scanned image of the interface structure at the joint of the sample constructed in Example 5 of this embodiment;

[0041] Figure 10 (a) A metallographic image of the interface structure at the joint of the sample constructed in Example 6 (Case 3). Figure 10 (b) is a scanned image of the interface structure at the joint of the constructed sample in Example 6 of this embodiment;

[0042] Figure 11 (a) Metallographic image of the interface structure at the joint of the sample constructed in Example 7 (Case 4). Figure 11 (b) is a scanned image of the interface structure at the joint of the sample constructed in Example 7 of this embodiment;

[0043] Figure 12 The substrate of Example 4 and the shear strength-displacement curves at the joints in Examples 4 to 7 are shown.

[0044] Figure 13 The images show the EBSD images of the interface region at the junction of the two constructed samples in Example 7, where (a) is the GB+IPF image of the interface region; and (b) is a statistical diagram of recrystallization, substructure, and deformed grain distribution in the interface region.

[0045] Figure 14 The images shown are TEM images of the interface region at the junction of the two constructed samples in Example 7, where (a) is a bright field image of a typical part of the interface region of the constructed joint, and (b) is a high-resolution image of the lattice arrangement of the interface healing part. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0047] Example 1:

[0048] like Figure 1 and Figure 2 As shown, the metal structure connection device in this embodiment includes a furnace body 1, a pressurization system, a heater 2, an upper support beam 3, a lower support beam 4, a water tank (not shown), a vacuum system, an electric field system, and an ultrasonic system.

[0049] As shown in Figure 1 and Figure 2 The upper support beam 3 and the lower support beam 4 are both arranged horizontally, and the lower support beam 4 is below the upper support beam 3, and the upper support beam 3 and the lower support beam 4 are supported by the column 5. Specifically, the column 5 is arranged vertically, and there are at least two. The structure of each column 5 is the same, and one of the columns 5 will be described below. The upper end of the column 5 is connected to the upper support beam 3, and the lower end of the column 5 is connected to the lower support beam 4.

[0050] The furnace body 1 is located in the space surrounded by the upper support beam 3, the lower support beam 4 and the two columns, and is a stainless steel furnace body. The upper support beam 3 is provided with a drive capable of driving the upper pressing column 10 to move up and down, and the drive is a hydraulic cylinder 6, the maximum output pressure of the hydraulic cylinder 6 is 50T, and the hydraulic cylinder 6 is electrically connected with the hydraulic pump station 7.

[0051] The inside of the furnace body 1 is hollow to form a chamber 1a, and the furnace body 1 has a water flow channel (not shown) for cooling the chamber 1a, which is located on the periphery of the chamber 1a, and the water flow channel is formed in the wall of the furnace body 1. The water tank is used to pump liquid into the water flow channel, and the water tank has a first through hole connected to the inlet of the water flow channel and a second through hole connected to the outlet of the water flow channel. In this way, when the chamber needs to be cooled, the water in the water tank is pumped into the water flow channel. In addition, the chamber 1a is also provided with a thermocouple. There are two kinds of thermocouples: when the experimental temperature is ≤600℃, K-type thermocouple is used; when the experimental temperature is ≥1000℃, S-type thermocouple is used; when the experimental temperature is 600℃-1000℃, both kinds of temperature measuring thermocouples can be used.

[0052] The pressurizing system of the embodiment includes an upper pressing column 10 and a lower pressing column 11 for placing the construction sample thereon, and the upper pressing column 10 and the lower pressing column 11 are both arranged vertically and partially located in the chamber 1a, and the upper pressing column 10 is above the lower pressing column 11 and is arranged to move towards the lower pressing column 11 to press the construction sample on the lower pressing column 11. Specifically, the upper end of the upper pressing column 10 is connected to the hydraulic cylinder 6, and the upper pressing column 10 is provided with an expansion pipe 8 connected with the furnace body 1 in a sealing manner, and the expansion pipe 8 of the embodiment is a bellows. The upper pressing column 10 is partially located in the chamber 1a.

[0053] The heater 2 is used to heat the construction sample in the chamber 1a, and is an annular heater arranged in the chamber of the furnace body 1. The annular heater can adopt the structure of the annular heating tube in the prior art, or other structure forms. In the present embodiment, the details will not be described again. The vacuum system is connected with the chamber 1a and located behind the furnace body 1, and is used to vacuumize the chamber 1a. The vacuum system adopts the vacuum system in the prior art, such as including a mechanical pump and a molecular pump. The mechanical pump and the molecular pump are combined together through a vacuum pipeline, and are installed at the back of the furnace body through a sealing interface. In the present embodiment, the details will not be described again.

[0054] The electric field system is used to apply an electric field to the construction sample, and is partially located in the chamber 1a. The aforementioned electric field system includes an electric field electrode, an electric field transformer 15, and a controller electrically connected with the electric field transformer 15. The controller is a current / voltage adjusting controller. The electric field transformer 15 is electrically connected with the positive electrode and the negative electrode respectively, and the electric field transformer 15 is located outside the furnace body 1. The electric field electrode includes the positive electrode and the negative electrode. The positive electrode is arranged on the upper pressing column 10 and is an integral part with the upper pressing column 10. The negative electrode is arranged on the lower pressing column 11 and is an integral part with the lower pressing column 11. In addition, the construction sample can be directly placed on the lower pressing column, or indirectly arranged on the lower pressing column 11. Specifically, the top end of the lower pressing column 11 is provided with a sample table (not shown) for placing the construction sample thereon. The sample table is movably arranged on the lower pressing column 11. The sample table can be manually moved up and down, or driven up and down by a driving mechanism. In addition, the sample table and the lower pressing column can be connected by the way of inserting a column into a slot. In the present embodiment, the details will not be described again.

[0055] The aforementioned sample table, the lower pressing column 11 and the upper pressing column 10 are all electrically conductive parts made of graphite material, and the sample table and the lower pressing column 11 can always conduct electricity. The electric field transformer 15 outputs current to the electric field electrode through a conductive sheet (such as a copper plate). The positive electrode is in contact with the upper surface of the construction sample by moving downward with the upper pressing column, and the negative electrode is in contact with the lower surface of the construction sample through the sample table. The electric field electrode adopts a graphite electrode. The electric field transformer has a rated power of 20 KW, a maximum working voltage of 10 V, and a maximum working current of 2000 A. When the electric field needs to be applied, 380 V high voltage is rectified by the electric field transformer 15 and then introduced into the electric field electrode through the conductive sheet. The positive electrode is in contact with the upper surface of the construction sample by moving downward with the upper pressing column, and the negative electrode is in contact with the lower surface of the construction sample through the sample table. The current / voltage adjusting controller can output the electric field. The working principle of the electric field is the same as that in the prior art. In the present embodiment, the details will not be described again.

[0056] The ultrasonic system is used to apply ultrasonic field to the built-up sample and is locally positioned in the chamber 1a. The ultrasonic system comprises an ultrasonic probe, an ultrasonic generator 17, a horn 13 and an ultrasonic transducer electrically connected with the ultrasonic generator 17, and the ultrasonic generator 17 and the ultrasonic transducer are positioned outside and below the furnace body 1. The ultrasonic probe is built in the lower pressing column 11 and indirectly contacts with the built-up sample. One end of the horn 13 is electrically connected with the ultrasonic probe, and the other end of the horn 13 is electrically connected with the ultrasonic transducer. Specifically, the lower end of the lower pressing column 11 is connected with the horn 13, and the lower end of the lower pressing column 11 is made of stainless steel. The rated power of the ultrasonic generator is 3KW, the rated frequency is 20KHz, the maximum amplitude of the ultrasonic probe is 20μm, and the amplitude of the ultrasonic probe transmitted to the joint of the two built-up samples stacked on the sample table is basically 1μm. The working principle of generating ultrasonic field by the ultrasonic generator, the ultrasonic transducer, the horn and the ultrasonic probe is the same as that of the prior art, and the embodiment will not be described in detail.

[0057] The total control station 14 is positioned on the right side of the furnace body, and the controller, the digital display screen, the electric field transformer 15, the air switch and the like are integrated thereon. The purpose and function of the total control station 14 are the same as those of the total control station of the prior art, and the embodiment will not be described in detail.

[0058] The total control station 14 controls the hydraulic pump station to drive the piston of the hydraulic cylinder 6 and the movement of the upper pressing column, and the upper and lower pressing columns press and fix the two built-up samples stacked on the sample table to complete the assembly; the total control station 14 controls the vacuum system to work to perform vacuumization on the chamber of the furnace body; and the total control station 14 starts the heater to heat the built-up sample and controls the electric field system and the ultrasonic system to apply electric field and ultrasonic field to the built-up sample.

[0059] The vacuum system, the heater, the pressurizing system, the electric field system and / or the ultrasonic system in the metal built-up device are integrated, have small volume, can complete the functions of pressurizing assembly, heating and applying electric field and / or ultrasonic field in the metal built-up connecting device, avoid the complexity caused by the need of transporting the equipment to the next process after heating is completed, i.e. reduce the process of built-up connection, and are beneficial to improve the production efficiency and reduce the energy consumption of metal built-up connection.

[0060] The terms denoting orientation, such as "front", "back", "upper", "lower", "left", "right", "side", "top", "bottom", and the like, are used in the description and claims of the present application to describe various example structural parts and elements of the present application, but are used only for the convenience of description and are determined based on the example orientation shown in the drawings. Since the disclosed embodiments of the present application can be arranged in different directions, these terms denoting orientation are only for illustration and should not be considered as limiting, such as "upper" and "lower" are not necessarily limited to the direction opposite or consistent with the direction of gravity.

[0061] The pre-connection method of the construction substrate interface of the present embodiment comprises the following steps in sequence:

[0062] Step 1) Two construction samples are cut from ultra-fine crystal nanometer carbon tube aluminum-based composite material (CNTs / Al-4Cu-Mg) After the two construction samples are milled flat on the surface to be connected, they are ground and polished to a surface roughness Ra≤0.8, and then ultrasonic cleaning and blowing dry are performed;

[0063] Step 2) The two 316H construction samples after surface treatment are butted and placed in the center of the sample table, and the height of the sample table is adjusted so that the distance L between the ultrasonic probe and the connection of the two construction samples is 12 cm;

[0064] Step 3) Start the pressurization system, move the upper press column downward by the hydraulic pump, and apply a top-down stress field to the two construction samples on the sample table for pre-pressing, and the pre-pressing pressure is 5 MPa. At this time, the two construction samples are pressed and fixed to complete the pre-assembly. Then, the length and angle of the thermocouple inserted into the chamber 1a are artificially adjusted by the sealing gasket, the thermocouple tip coated with an insulating layer is tightly attached to the construction sample interface, and real-time accurate measurement of the construction sample temperature is realized. Finally, the sealing gasket for locking the thermocouple is locked, and the assembly of the construction sample is completed;

[0065] Step 4) Close the furnace body, start the vacuum and cooling circulation system, and when the vacuum degree in the furnace body chamber reaches 1.0×10 -3 Pa, start the heater to radiate and heat the construction sample. Temperature field setting process: first heat the sample quickly to T1=430℃ at V1=10℃ / min, then slowly heat to T2=485℃ at V2=5℃ / min, and keep the temperature field at T2=485℃ for t0=120min.

[0066] Step 5) When the temperature of the construction sample reaches T2=485℃, first heat the sample for 20min; then continue to move the upper press column downward by the hydraulic pump, apply a P3=30-50MPa stress field to the construction sample, and make the construction sample move at a speed of 5×10-3 s -1 plastic deformation; when the strain reaches 40%, the stress field is reduced to P2=10 MPa to continue to keep pressure for 60 min, and the build sample does not continue to deform under this pressure; immediately after the build sample completes deformation, the electric field transformer is started to adjust the electric field current / voltage parameters, and the electric field of 40 A / cm2current density is applied to the build sample through the electric field electrode, and acts for t1=20 min to further promote interface healing. In this build connection process, the total working time of the stress field is 60 min, and the total holding time of the temperature field after heating is 120 min. 2

[0067] The two CNTs / Al-4Cu-Mg build samples in this embodiment gradually tend to be traceless connection after the joint action of the temperature field, the stress field and the electric field, and the interface structure after connection is shown in Figure 3 and Figure 4 The interface structure at the connection is located between the two horizontal dashed lines. On the one hand, the ultra-fine-grained aluminum-based composite material itself has a short diffusion channel, and atoms are easy to realize cross-interface diffusion to promote interface healing; on the other hand, the joint action of the temperature field, the stress field and the electric field promotes the decomposition and diffusion of the interface oxide.

[0068] Example 2:

[0069] The difference between this embodiment and the above-mentioned embodiment 1 is only that:

[0070] 1. In step 1), the material of the build sample is different, specifically, the material of the build sample is selected as AZ31 magnesium alloy.

[0071] 2. The setting process of the temperature field in step 4) is different, specifically, the sample is first heated to T1=400℃ at V1=10℃ / min, then slowly heated to T2=450℃ at V2=5℃ / min, and kept at T2=450℃ for t0=120 min.

[0072] 3. Step 5) is different, specifically, when the temperature of the build sample reaches T2=450℃, the upper pressing column is continuously moved downward by the hydraulic pump to apply a stress field of P3=30-40 MPa to the build sample, so that the build sample occurs intense plastic deformation at a strain rate of 5×10 -4 s -1 When the strain reaches 35%, the stress field is reduced to P2=10 MPa to continue to keep pressure for 90 min.

[0073] In this embodiment, the two AZ31 magnesium alloy build samples are jointly acted by the temperature field and the stress field, and the interface structure after connection is shown in Figure 5 ​As shown, the connection interface zone of the two built samples has a relatively complete uncracked oxide layer of about 2 μm, and the thickness of the uncracked oxide layer is small.

[0074] Example 3:

[0075] The difference between this example and the above-described example 2 is only that: 1. In step 5), when the temperature reaches T2=450 ℃, the upper pressing column is driven to continue moving downward by a hydraulic pump to apply a stress field of P3=30-40 MPa to the built sample, so that the built sample plastically deforms at a strain rate of 5x10 -4 s -1 When the strain reaches 35%, the stress field is reduced to P2=10 MPa to continue pressure keeping for 90 min; when the sample starts to deform, the electric field transformer and the ultrasonic generator are started at the same time to adjust the electric field and ultrasonic field parameters, an electric field of 40 A / cm 2 current density is applied to the sample by the electric field electrode for 20 min, and an ultrasonic field of an amplitude of about 1 μm is applied to the interface of the sample by the ultrasonic probe for 5 min.

[0076] In this example, after the two AZ31 magnesium alloy built samples are subjected to the combined action of the temperature field, the stress field, the electric field and the ultrasonic field, the oxides in the refractory interface oxide layer have been broken and decomposed, i.e., the decomposition and diffusion of the interfacial alloying elements are promoted, and the interface in the partial region has been healed. The interface structure after connection can be seen from Figure 6 .

[0077] Example 4:

[0078] The difference between this example and the above-described example 2 is only that:

[0079] In step 1), a commercial AZ31 magnesium alloy ingot is wire cut into a sample of Ф40x20 mm, the upper and lower surfaces of the sample are milled to ensure parallelism, the connection surfaces are polished with 240#, 400#, 800#, 1000# and 1200# sandpaper, and then polished with a velvet cloth, and then placed in industrial ethanol for ultrasonic cleaning for 2 minutes and then blown dry by cold air;

[0080] The setting process of the temperature field in step 4) is different, and specifically, as shown in Figure 7 , the sample is first rapidly heated to T1=420 ℃ at a heating rate of V1=10 ℃ / min, then slowly heated to T2=450 ℃ at a heating rate of V2=5 ℃ / min, and kept at a temperature field of T2=450 ℃ for t0=120 min (the first 10 min makes the built sample fully cooked, the subsequent 10 min makes the built sample compressively deform, and the last holding time is for pressure keeping); then, the sample is cooled in the furnace; during this period, the stress field is kept at P2=15 MPa;

[0081] Step 5) differs from the previous one. Specifically, when the temperature field reaches T2 = 450℃, the hydraulic pump drives the upper pressure column to continue moving downwards, applying a stress field of P3 = 35MPa to the constructed sample, causing the constructed sample to move at a stress of 5 × 10⁻⁶ MPa. -4 s -1 The strain rate causes severe plastic deformation; when the strain reaches 35%, the stress field is reduced to P2 = 15MPa and the pressure is maintained until the end of the test.

[0082] The above T2 = (0.6~0.85)T m T m Where P is the melting point of the material; P3 = (1.2~1.5)σ 0.2 P2 = (0.5 ~ 0.8)σ 0.2 , σ 0.2 The high-temperature yield strength of the material used to construct the sample.

[0083] The constructed samples were only treated with temperature and stress fields before being... Figure 8 It can be concluded that the tissue at the interface of the two constructed samples has a certain healing effect, but there are still a large number of undecomposed interface oxides and pore gaps, and the connection quality needs to be further improved.

[0084] like Figure 12 It can be seen that, under the action of temperature and stress fields, the connection strength at the joint of the constructed sample in this embodiment is only 38% of the strength of the base material (constructed sample).

[0085] Example 5:

[0086] The only difference between this embodiment and the above embodiment 4 is that in step 5), an ultrasonic field was applied for 5 minutes at the beginning of the self-plastic deformation of the sample, and the ultrasonic frequency was selected as 20KHz.

[0087] After being treated with temperature, stress, and ultrasonic fields, the constructed samples were then subjected to... Figure 9 It can be concluded that the oxide layer at the interface between the two constructed samples began to break due to local deformation and bending. Under the action of the ultrasonic field, the thickness of the oxide layer at the interface was reduced to about 1 μm, which means that the thickness of the oxide layer was reduced, and the beneficial effect was initially shown.

[0088] like Figure 12 It can be seen that, under the influence of temperature, stress, and ultrasonic fields, the connection strength at the joint of the constructed sample in this embodiment is 41.3 MPa, reaching 38.6% of the strength of the substrate (constructed sample). The quality of the joint of the constructed sample is reflected by the connection strength, and the connection strength increases after the ultrasonic field is added.

[0089] Example 6:

[0090] The difference between this embodiment and the above-mentioned embodiment 5 is that in step 5), the electric field is applied to the construction sample from the beginning of plastic deformation for t1=10 min, and the current density I1 is 20 A / cm 2 .

[0091] After the construction sample is treated by the temperature field, the stress field and the electric field, the construction sample is Figure 10 It can be concluded that the thickness of the oxide layer in the connection interface region of the two construction samples is obviously reduced under the effect of the electric field thermal effect, and the phenomenon of complete decomposition of the oxide and complete healing of the interface has appeared locally. It is worth noting that although there are still undecomposed oxides and incompletely healed regions in the micro-selected area, the overall metallurgical bonding effect of the weak interface of the oxide layer is good, and the construction joint structure has been greatly improved under this condition.

[0092] As shown in Figure 12 , under the action of the temperature field, the stress field and the electric field, the connection strength of the construction sample connection in this embodiment is 76.8 MPa, reaching 71.7% of the strength of the base material (construction sample). After increasing the electric field, the connection strength is obviously increased.

[0093] Embodiment 7:

[0094] The difference between this embodiment and the above-mentioned embodiment 4 is that in step 5), the ultrasonic field of 20 KHz and the electric field of current density I1 of 40 A / cm 2 are applied to the construction sample from the beginning of plastic deformation, the action time of the ultrasonic field is 5 min, and the action time t1 of the electric field is 30 min.

[0095] As shown in Figure 12 , under the combined action of the temperature field, the stress field, the electric field and the ultrasonic field, the connection strength of the construction sample connection in this embodiment is 91.8 MPa, reaching 85.7% of the strength of the base material (construction sample). Compared with the construction joint without external field assistance, the connection strength of the construction joint under the combined action of the ultrasonic field and the electric field has been greatly improved.

[0096] As shown in Figure 11 and Figure 13As shown, the interface pre-joining of the build-up substrate based on the temperature field and stress field shows good healing effect under the coupling of ultrasonic field and electric field, and tends to be traceless joining. The interface oxide layer is softened and torn by the temperature field and stress field, exposing the fresh metal for local metallurgical bonding; the ultrasonic field performs ultrasonic micro-oscillation on the torn oxide layer in this process, the interface micro-area is fully contacted and ground, so that the torn oxide layer is further broken and decomposed, and the deformed grains near the interface are stimulated to produce recovery and dynamic recrystallization, forming a large number of fine DRX grains in the interface area; the electric field produces thermal effect and electric field force on the interface oxide with resistivity much greater than that of the metal itself, and promotes the decomposition of high-melting-point oxide at a local high temperature without burning the substrate, and also accelerates the directional movement of electrons to make the atoms at the interface quickly diffuse to the substrate; finally, under the synergistic action of multiple fields, the interface is healed in most areas with the formation and growth of a large number of DRX, substructure and deformed grains.

[0097] Under the regulation of complex fields such as temperature field, stress field, electric field and ultrasonic field, the essence of the interface pre-joining of the build-up substrate is that the atoms at the interface are in a high-energy state due to the external energy input, and can quickly diffuse to realize lattice coordination bonding under the synergistic action of multiple fields. Figure 14 As shown, through TEM bright-field image observation, it can be seen that the connection at the healed interface of the build-up joint interface area after the action of the complex fields is a nanoscale effective bonding, and the residual interface layer oxide has been decomposed and diffused into the substrate, and the pre-joining interface becomes similar to the internal interface of the crystal. In addition, the lattice arrangement at the interface healing site can be observed by high-resolution TEM image, and the orientation matching relationship between the adjacent grains in crystallography further proves the feasibility of the complex field regulated build-up substrate interface pre-joining method.

[0098] Example 8:

[0099] The difference between this embodiment and the above-mentioned example 7 is only that:

[0100] Step 5) is different, specifically, when the temperature field reaches T2=450℃, the upper pressing column is continuously moved downward by a hydraulic pump to apply a stress field of P3=50MPa to the build-up sample, so that the build-up sample occurs intense plastic deformation at a strain rate of 10 -1 s -1 When the strain reaches 5%, the stress field is reduced to P2=12MPa and continues to be pressed to the end of the test, and the whole pressure holding time is 1h.

[0101] In step 5), the build-up sample is subjected to ultrasonic field of 20KHz and electric current density I1 of 30A / cm 2The electric field and ultrasonic field are applied for 10 minutes, and the electric field is applied for 20 minutes (t1). After the ultrasonic and electric fields end, the temperature and stress fields should continue to act for a period of time. The holding temperature is 450℃, the holding time is 1 hour, the holding stress is 50 MPa, and the total holding time is 1 hour.

[0102] Example 9:

[0103] The only difference between this embodiment and embodiment 7 above is that:

[0104] 1. The material used for constructing the sample is aluminum alloy or 316H stainless steel, and T2 is 550℃; step 5) is different. Specifically, when the temperature field reaches T2=550℃, the upper pressure column is driven by a hydraulic pump to continue moving downward, applying a stress field of P3=40MPa to the constructed sample, so that the constructed sample is subjected to a stress field of 10 -5 s -1 The strain rate causes severe plastic deformation; when the strain reaches 60%, the stress field is reduced to P2 = 12MPa and the pressure is maintained until the end of the test.

[0105] In step 5), a 20 kHz ultrasonic field and a current density I1 of 30 A / cm² are applied simultaneously with the start of the self-plastic deformation of the constructed sample. 2 The electric field and ultrasonic field are applied for 10 minutes, and the electric field is applied for 20 minutes (t1). After the ultrasonic and electric fields end, the temperature and stress fields should continue to act for a period of time. The holding temperature is 550℃, the holding time is 2 hours, the holding stress is 40 MPa, and the total holding time is 2 hours.

[0106] In the above embodiments, the two constructed samples selected are made of the same homogeneous metallic material. In the above embodiments, the area between the two horizontal dashed lines in the metallographic image and scanning image of the constructed samples represents the area connecting the two corresponding constructed samples. In the above embodiments and claims, rapid heating refers to adjusting the current / voltage of the annular heater to achieve a heating rate greater than or equal to 10°C / min within the stainless steel furnace chamber; slow heating refers to adjusting the current / voltage of the annular heater to achieve a heating rate less than or equal to 5°C / min within the stainless steel furnace chamber.

[0107] In the above embodiments, the temperature field continues from the start of the heater until the end of the experiment.

Claims

1. A pre-connection method for constructing a substrate interface, characterized in that, The steps are as follows: 1) After smoothing the surfaces of the two constructed samples, grind and clean them; 2) Connect and stack the two constructed samples in the sample stage inside the furnace chamber; 3) Apply a downward stress P1 to the two structural samples using a pressurization system to pre-fix them; 4) Evacuate the furnace chamber and heat the constructed sample inside, i.e., apply a temperature field to the constructed sample. The temperature field setting process is as follows: first, rapidly heat the constructed sample to T1 at a heating rate V1, then slowly heat the constructed sample to T2 at a heating rate V2, and hold at that temperature for a period of time, where V1 > V2 and T1 < T2; during the heating process, maintain the stress at P2; temperature T2 = (0.6~0.85)T m T m The melting point of the material is V1 = 10℃~15℃ / min, V2 = 1℃~5℃ / min, T1 = 400℃~1000℃, T2 = 450℃~1200℃, P1 = 5MPa~10MPa, P2 = 10MPa~15MPa, P3 = 30MPa~50MPa; 5) When the temperature reaches T2, continue to apply a downward stress P3, where P3 > P1, to the two constructed samples using the pressurization system. After holding the pressure for t2, or until the constructed samples are subjected to a strain rate of (10... -5 ~10 -1 )s -1 Plastic deformation occurs, and after the strain reaches (5%~60%), the stress is reduced to P2 and held at that pressure, where P3 > P2 > P1, meaning a varying stress field is applied to the constructed sample; stress P3 = (1.2~1.5)σ 0.2 P2 = (0.5~0.8)σ 0.2 , σ 0.2 The high-temperature yield strength of the material used to construct the sample.

2. The pre-connection method according to claim 1, characterized in that: Following step 5), a top-down electric field is applied to the constructed sample. The rated power of the electric field transformer in the electric field system generating the electric field is 20KW, the maximum operating voltage of the electric field is 10V, and the maximum operating current is 2000A. An electric field with a current density of I1 is applied to the constructed sample through the electric field electrodes, and the electric field is maintained for a time t1, where I1 is 0~400A / cm. 2 t1 is 0~60min.

3. The pre-connection method according to claim 1, characterized in that: After step 5), an ultrasonic field is applied to the constructed sample. An ultrasonic probe is provided below the sample stage to perform ultrasonic treatment on the constructed sample. The height of the sample stage is adjusted as needed, that is, the distance between the interface of the two constructed samples and the ultrasonic probe is adjusted to L, where L is an integer multiple of the ultrasonic wavelength, so that the interface is located at the point where the ultrasonic wave peaks overlap.

4. The pre-connection method according to claim 3, characterized in that: The ultrasonic generator electrically connected to the ultrasonic probe has a rated power of 3KW and a rated frequency of 20KHz. The distance L between the ultrasonic probe and the sample interface is 12cm. The maximum amplitude of the ultrasonic probe is 20μm. The amplitude transmitted from the ultrasonic probe to the sample interface is 1μm.

5. The pre-connection method according to claim 1, characterized in that: After step 5), an ultrasonic field and a top-down electric field are simultaneously applied to the constructed sample. The rated power of the electric field transformer in the electric field system is 20KW, the maximum operating voltage of the electric field is 10V, and the maximum operating current is 2000A. The ultrasonic system generates an ultrasonic field, and the rated power of the ultrasonic generator in the ultrasonic system is 3KW, the rated frequency is 20KHz, and an ultrasonic probe is set below the sample stage to perform ultrasonic treatment on the constructed sample. The distance L between the interface of the constructed sample and the ultrasonic probe is 12cm, the maximum amplitude of the ultrasonic probe is 20μm, and the amplitude transmitted by the ultrasonic probe to the connection of the constructed sample is 1μm.

6. The pre-connection method according to claim 5, characterized in that: After the ultrasonic and electric fields have ended, the temperature and stress fields should continue to act for a period of time, with the holding temperature being (0.6~0.85) T. m The heat preservation time is 0 h ~ 2 h; the compressive stress is (0.5~0.8)σ. 0.2 The pressure holding time is 0 h ~ 2 h.

7. The pre-connection method according to claim 1, characterized in that: The constructed sample is one of magnesium alloy, aluminum alloy, ultrafine crystalline carbon nanotube aluminum matrix composite material, or 316H stainless steel.

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